Sildenafil citrate is found in silagra 100 tablets as a generic brand. It is mostly used to treat erectile dysfunction in men. The effect of this drug lasts for 4 to 6 hours. And if the effect of this medicine lasts for more than 6 or 4 hours, seek the help of a doctor immediately. See a doctor's advice before increasing or decreasing the dosage of this medicine to see the good effect of this medicine. Take this medicine only once in 24 hours.